Swivel chair



FIG. 1 shows a front perspective view of our design for a swivel chair;

FIG. 2 shows a rear perspective view thereof;

FIG. 3 shows a front elevational view thereof;

FIG. 4 shows a right side view thereof;

FIG. 5 shows a rear elevational view thereof; and,

FIG. 6 shows a top view thereof. 

The ornamental design for a swivel chair, as shown and described. 